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core_addshmem_write.5 (2010 09)

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core_addshmem_write(5) core_addshmem_write(5)
(Tunable Kernel Parameters)
NAME
core_addshmem_write - determines the inclusion of read/write shared memory in process core dump
VALUES
Failsafe
0 (off)
Default
0 (off)
Allowed values
1 (on) or 0 (off)
DESCRIPTION
The
core_addshmem_write
tunable was added in response to a problem where a customer was lim-
ited in debugging a user-level process crash because shared memory segments were not written as part of
the core file.
Upon core dump, the sections of user memory labeled as shared read-write are written (along with the
normal data sections) if this tunable is set to
1 (on), and left out if it is set to 0 (off).
Who is Expected to Change This Tunable?
Anyone.
Restrictions on Changing
Changes to this tunable take effect immediately.
When Should the Value of This Tunable Be Raised?
When you wish to include read-write shared memory segments in user core files due to debugging needs
by developers or maintainers on the system.
What Are the Side Effects of Raising the Value?
User process core files would increase in most cases (most applications use at least some shared memory).
This could be a problem on systems where disk space is at a premium.
When Should the Value of This Tunable Be Lowered?
When there is no need for debugging core files where shared memory corruption or data values are in
question.
What Are the Side Effects of Lowering the Value?
Core files will tend to be smaller.
What Other Tunable Values Should Be Changed at the Same Time?
Certainly think about
core_addshmem_read, which does the same thing for read-only shared memory
segments.
WARNINGS
All HP-UX kernel tunable parameters are release specific. This parameter may be removed or have its
meaning changed in future releases of HP-UX.
Installation of optional kernel software, from HP or other vendors, may cause changes to tunable parame-
ter values. After installation, some tunable parameters may no longer be at the default or recommended
values. For information about the effects of installation on tunable values, consult the documentation for
the kernel software being installed. For information about optional kernel software that was factory
installed on your system, see HP-UX Release Notes at http://www.hp.com/go/hpux-core-docs.
AUTHOR
core_addshmem_write was developed by HP.
ALSO
kctune(1M).
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

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